Written by Per McCord, Cherry breeder, Washington State University 5 March 2025.
As leader of the Washington State University cherry breeding program (CBP), I am excited to report on some of the key outcomes of our work since the relaunch of the program in 2018. The CBP is based at the Irrigated Agriculture Research and Extension Center in Prosser. Our goal is to develop superior sweet cherry cultivars for Pacific Northwest growers.
The CBP is set up as a multi-stage pipeline. At the crossing stage, parents and cross combinations are carefully chosen to target industry priorities. Our main targets are fruit size, firmness, and early (or late) ripening time. Additional priorities include self-fertility, disease resistance (powdery mildew and X-disease), and crack resistance.
Seedlings from these crosses make up Phase 1. Each tree in Phase 1 is unique, and represents a potential new variety. More than 3000 new Phase 1 seedlings have been planted in the last three years. Prior to planting, the CBP uses DNA testing to eliminate inferior seedlings. We have successfully deployed newly developed DNA tests for fruit firmness and cracking along with existing tests for self-fertility and powdery mildew, eliminating > 1200 inferior seedlings at the greenhouse stage. Removing these seedlings before they are planted in the field saves thousands of dollars in planting, management, and evaluation costs. Seedlings usually take from 2-3 years to begin fruiting, and are evaluated for 2-3 seasons. We walk through the seedling blocks twice per week during the harvest season, sampling seedlings for fruit size, firmness, and flavor. Fruit from the best seedlings are taken to the fruit quality lab where we measure them for size, firmness, defects, cracking, Brix, and titratable acidity.
The best-performing seedlings are advanced to Phase 2. Our selection criteria are rigorous; over the past 3 years, only 3 seedlings have been advanced to Phase 2, which currently has a total of 13 selections. These trials are in 4 locations in Washington and Oregon. Each selection is grafted onto a rootstock (Gisela-12 or Gisela-6), and we plant 15 trees per selection at each location. Fruit in Phase 2 are evaluated as for Phase 1, with the addition of postharvest quality and stem pull force. Selections in Phase 2 are evaluated for 3 seasons once they begin fruiting.
Of the currently fruiting Phase 2 selections (Table 1), R47 is the earliest, ripening more than a week before ‘Bing’. It is the firmest cherry in our current Phase 2 trials, with excellent size (especially for the timing) and strong flavor. CR01T078 ripens generally a few days after ‘Bing’ and has very large fruit with good flavor. R45 is the latest of the group, ripening with or slightly later than ‘Skeena’. It is self-fertile, with very large fruit. R35B is the lone blush selection in this group. It ripens 3-4 days after ‘Rainier’. Crops are lighter, but fruit size is very large with excellent firmness, and the tree is self-fertile. Pending a favorable harvest in 2025, we expect to advance several of these selections to Phase 3 trials.
Table 1. Characteristics of R47, CR01T078, R45, and R35B (Phase 2), with ’Benton’, ‘Bing’, ‘Rainier’, and ‘Skeena’ as standards. Performance results are from the 2024 season. Results are averaged (where possible) across 3 locations [IAREC (Prosser), Sagemoor (Pasco), and MCAREC (Hood River)].
| Selection | S-alleles | Timing (vs. ‘Bing’) | Weight (g)/ Row size | Firmness (g/mm)1 | °Brix/TA | Notes |
|---|---|---|---|---|---|---|
| R47 | S1S9 | -8 | 12.5/8.4 | 303 | 22.6/0.73 | Firm, strong flavor |
| ‘Benton’ | S4’2S9 | -5 | 9.3/9.8 | 248 | 25.4/0.92 | Standard |
| ‘Bing’ | S3S4 | 0 | 9.2/9.9 | 206 | 22.0/0.59 | Standard |
| CR01T078 | — | +3 | 12.6/9 | 252 | 22.2/0.60 | Good size, flavor |
| ‘Skeena’ | S1S4’ | +9 | 11.2/9.6 | 243 | 22.7/0.45 | Standard |
| R45 | S4’S9 | +8 | 13.4/8.7 | 258 | 23.6/0.49 | Consistent yield across sites |
| ‘Rainier’ | S1S4 | -1 | 9.7/10 | 208 | 21.4/0.41 | Standard |
| R35B | S4’– | +2 | 13.9/8.6 | 292 | 22.7/0.42 | Very large, lighter crops vs. ‘Rainier’ |
Footnotes: 1Firmness measured on fruit at room temperature. 2Self-fertile allele.
Phase 3 is the final stage before a cultivar is considered for release as a new variety. These are larger plantings (generally 100 trees or more), and the goal is to get enough fruit to run over a commercial packing line. As for Phase 2, we evaluate Phase 3 trials for three harvests. Of the 3 selections in Phase 3, the evaluation cycle is nearly complete for 2 of them.
R19 (Fig. 1) is early ripening (‘Chelan’ timing), but self-fertile with larger fruit, greater firmness, and higher SSC (°Brix) than ‘Chelan’ (Table 2). The high sugar levels of R19 make it susceptible to bird predation, and it is susceptible to nose cracks, although we have not seen cracking in all years. Eating quality of R19 is superb. Small amounts of certified budwood of R19 were sent to local nurseries in 2022 and again in 2024.
R3 (Fig. 2) ripens 4-7 days later than ‘Chelan’ but is considerably larger and sweeter, with comparable firmness (Table 2). R3 also has good hang time and a meaty texture. Budwood of R3 was sent to interested nurseries in Fall 2024. R3 has tested positive for cherry virus A (CVA). Although CVA has no known negative impacts, the CBP is continuing efforts to obtain clean wood of R3.
Table 2. Characteristics of R19 and R3 (Phase 3), with ‘Chelan’ as a standard. Performance results are from 2024 season. Estimated yield and packout data are from the entire trial, which was harvested and run over a commercial packing line; all other results are based on fruit pooled from 5 trees and evaluated in the breeding program fruit lab.
| Selection | S-alleles | Harvest Date | Weight (g)/Row size | Firmness (g/mm) | Brix/TA | Estimated Yield/Packout | Location |
|---|---|---|---|---|---|---|---|
| R19 | S4’1S9 | 6/6 | 8.3/10.0 | 335 | 23.1/0.28 | 7.3 tons/89% | Mattawa |
| R3 | S1– | 6/10 | 11.4/9.0 | 285 | 25.3/– | — (small trees) | Mattawa |
| ‘Chelan’ | S3S9 | 6/6 | 5.8/Under | 319 | 17.3/0.44 | 4.6 tons/93% | Mattawa |
| R3 | 6/10 | 11.4/9.5 | 224 | –/– | 3.8 tons/78% | Buena | |
| ‘Chelan’ | 6/3 | 7.0/11.5 | 212 | 17.8/0.31 | — | Buena |
Footnotes: 1Self-fertile allele.
Pending a favorable harvest in 2025, Dr. McCord will recommend to the WSU Variety Release Committee that R3 and R19 be released as new cultivars. R19 could be available for commercial pre-orders as early as spring 2026. R3 will likely be 1-2 years behind this due to budwood availability. Stay tuned for another update during the summer!
Contact
Per McCord
Washington State University
phmccord@wsu.edu
509-786-9254
Funding and acknowledgements
This research was funded by the Washington Tree Fruit Research Commission and the Oregon Sweet Cherry Commission.
Additional information
PNW cherry breeding and genetics program
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